The Gaon writes (Yeshayahu 6:9) "It is the Yetzer Hara
who prevents people from learning Kabalah. He knows
that by learning Kabalah a person will do Teshuva Shleimah.
The ספר אבן שלמה quotes the Gaon "Whoever was capable
to understand Kabbalah but didn't attempt to understand it will
be punished for it Leasid Lavo."(8:24)
He also quotes the Gaon " As long as you don't understandSod (Kabalah), you won't have clarity in Pshat."(8:21)